Generate random points within quad

generate_points.py

import random
import numpy as np
from shapely.geometry import Point
from shapely.geometry.polygon import Polygon

points = [
    [0, 0],
    [0, 1],
    [1, 0],
    [1, 1]
]

triangles = points[0:3], points[1:4]

def triangle_area(triangle):
    v0, v1, v2 = triangle
    x0, y0 = v0
    x1, y1 = v1
    x2, y2 = v2

    return abs(0.5*(x0*(y0-y1)+x1*(y2-y0)+x2*(y0-y1)))

areas = [triangle_area(triangle) for triangle in triangles]
total_area = sum(areas)

weights = [area / total_area for area in areas]

for i, weight in enumerate(weights):
    print("Weight {} (area of Triangle {} / total area)")
    print(weight)


# currently works for 2 triangles
def pick_random(weights, triangles):
    if random.random() < weights[0]:
        i = 0
    else:
        i = 1

    print("picked triangle {}".format(i))

    a0 = random.random()
    a1 = random.random()

    print("a0: {}; a1: {}".format(a0, a1))

    v0, v1, v2 = [np.array(v) for v in triangles[i]]
    v3 = (v1 - v0) + (v2 - v0)
    p = a0 * (v1 - v2) + a1 * (v2 - v0)

    print("v0, v1, v2, v3: {}".format((v0, v1, v2, v3)))
    print("p: {}".format(p))

    polygon = Polygon([v0, v1, v2])

    if polygon.contains(Point(p)):
        return p
    else:
        print("not in triangle")
        p = v0 + (v3 - p)
        print(polygon.contains(Point(p)))
        return p


for i in range(10):
    print("random: {}".format(pick_random(weights, triangles)))
    print()